SACCHARINE AND ASTRINGENT EXUDATIONS OF GREY GUM. 189 
After long evaporation on the water bath, under boiling, it was 
still a thick syrup and was hygroscopic ; constant weight was 
obtained, however, by long heating when the loss was found to be 
10:16 per cent. When heated ata higher temperature, the sugars 
slowly decompose, becoming very dark, and the caramel odour most 
pronounced, the loss when heating for half an hour at 130° C. on 
‘4 gram sugars being about ‘01 gram for each of six determinations, 
the decomposition thus proceeding at an uniform rate. 
When fresh beer-yeast was added to a solution of this syrup, 
fermentation set up at once and proceeded rapidly. After the 
fermentation had ceased, the solution was found to still contain a 
sugar that appeared to be unfermentable while the temperature 
was about 16° to 18° C., and the solution of which was dextro- 
rotatory, and that reduced Fehling’s solution. 
A quantitative determination of these sugars was then made 
with the following result :—-231 gram of the dried sugars (allow- 
ing 10°16 as the percentage of water), evolved ‘0667 gram CO, or 
equivalent to -1364 gram of fermentable sugar considered as 
glucose, thus leaving -0946 gram of an unfermentable sugar 
at the temperature used: or, decomposed 59 per cent. and un- 
decomposed 41 per cent. By the method of precipitation used, it 
is tobe supposed that a small proportion of raffinose might be 
Present, which would partly ferment, and thus prevent a correct 
quantitative result being obtained ; but I think we may assume 
that the experiment shows these sugars to be present in about 
equal proportions, indicating that natural alteration of the 
raffinose had taken place corresponding to that undergone by this 
Sugar when treated with dilute acids. It was not thought desir- 
able to adopt chemical precipitation, so that alteration could not 
arise from that source. 
The whole of the remaining sugars I had obtained were then 
treated with yeast, so that the decomposable sugar might be 
removed by fermentation. The remaining sugar that was unfer- 
mentable at the temperature used, was then carefully prepared for 
